REDUCED FETAL EXPOSURE TO ASPIRIN USING A NOVEL CONTROLLED-RELEASE PREPARATION IN NORMOTENSIVE AND HYPERTENSIVE PREGNANCIES

Objectives To examine the fetal effects of a novel controlled-release, low dose aspirin preparation in normal and hypertensive pregnancies. Design Random double-blind study, Participants assigned to receive con ventional formulation aspirin (75 mg), controlled-release low close as pirin (75 mg), or a matching placebo. Setting National Maternity Hospi tal, Dublin. Participants Eighteen women with an uncomplicated pregnan cy and 18 women with preeclampsia. Main outcome measures Urine was ana lysed for metabolites of thromboxane and prostacyclin by gas chromatog raphy, mass spectrometry. Serum thromboxane B-2 was determined in mate rnal and cord blood. Results Bosh aspirin preparations reduced materna l serum thromboxane B-2 by 95% and induced similar reductions in the u rinary 11-dehydro-thromboxane B-2, a major metabolite of thromboxane A (2) in vivo. In contrast, neither preparation altered urinary 2,3-dino r-6-keto PGF(1 alpha), the major metabolite of prostacyclin. Despite t heir similar effects in the mothers, the two aspirin preparations diff ered in their effects on the fetus. While both suppressed cord fetal t hromboxane B-2, this was significantly (P < 0.005) less for the contro lled-release preparation (2.10 +/- 42 ng/ml for placebo vs 109 +/- 22 ng/ml for controlled-release aspirin and 44 +/- 9 ng/ml for regular or al aspirin). Conclusions Al equivalent maternal suppression of serum t hromboxane B-2, a controlled aspirin release preparation results in lo wer fetal exposure than regular oral aspirin.